include/asm-x86_64/tsc.h

   1 /*
   2  * linux/include/asm-x86_64/tsc.h
   3  *
   4  * x86_64 TSC related functions
   5  */
   6 #ifndef _ASM_x86_64_TSC_H
   7 #define _ASM_x86_64_TSC_H
   8
   9 #include <asm/processor.h>
  10
  11 /*
  12  * Standard way to access the cycle counter.
  13  */
  14 typedef unsigned long long cycles_t;
  15
  16 extern unsigned int cpu_khz;
  17 extern unsigned int tsc_khz;
  18
  19 static inline cycles_t get_cycles(void)
  20 {
  21         unsigned long long ret = 0;
  22
  23 #ifndef CONFIG_X86_TSC
  24         if (!cpu_has_tsc)
  25                 return 0;
  26 #endif
  27
  28 #if defined(CONFIG_X86_GENERIC) || defined(CONFIG_X86_TSC)
  29         rdtscll(ret);
  30 #endif
  31         return ret;
  32 }
  33
  34 /* Like get_cycles, but make sure the CPU is synchronized. */
  35 static __always_inline cycles_t get_cycles_sync(void)
  36 {
  37         unsigned long long ret;
  38 #ifdef X86_FEATURE_SYNC_RDTSC
  39         unsigned eax;
  40
  41         /*
  42          * Don't do an additional sync on CPUs where we know
  43          * RDTSC is already synchronous:
  44          */
  45         alternative_io("cpuid", ASM_NOP2, X86_FEATURE_SYNC_RDTSC,
  46                           "=a" (eax), "0" (1) : "ebx","ecx","edx","memory");
  47 #else
  48         sync_core();
  49 #endif
  50         rdtscll(ret);
  51
  52         return ret;
  53 }
  54
  55 extern void tsc_init(void);
  56 extern void mark_tsc_unstable(void);
  57 extern int unsynchronized_tsc(void);
  58
  59 /*
  60  * Boot-time check whether the TSCs are synchronized across
  61  * all CPUs/cores:
  62  */
  63 extern void check_tsc_sync_source(int cpu);
  64 extern void check_tsc_sync_target(void);
  65
  66 #endif